1. Field of the Invention
The present invention relates to a backlight module, and specifically to a backlight module having light emitting diodes.
2. Description of the Prior Art
Flat display panels and flat display devices using the flat display panels are becoming the mainstream of the display device. Especially, the liquid crystal devices are now very prominent amongst conventional flat display devices and are greatly used in electronic products such as display screens, household flat televisions, flat displays of personal computers and laptop computers, display screens of mobile phones, and digital cameras.
The backlight module is one of the key components of the conventional liquid crystal display panels. Due to the fact that liquid crystal does not generate light by itself, the backlight module is used to provide adequate and evenly distributed light for the liquid crystal display panels to display images.
FIG. 1 is a cross-sectional view of a conventional liquid crystal display device. As FIG. 1 shows, the conventional liquid crystal display device 10 includes a display panel 11, an optical film set 12, a light guide plate 13, a reflector 14 and an outer frame 15. The optical film set 12, the light guide plate 13 and the reflector 14 are disposed on the outer frame 15. The optical film set 12 includes optical films such as reflective polarizer, diffusion plate, and prism plate for processing light emitted from the light guide plate 13. Furthermore, the conventional liquid crystal display device 10 includes a light source (not illustrated) disposed next to the light guide plate 13 and configured to emit light into the light guide plate 13. As FIG. 1 shows, a first light 16 and a second light 17 exist in the light guide plate 13, wherein the first light 16 exits from the bottom of the light guide plate 13 and is then dispersed by the reflector 14 into lights of different directions. The first light 16 dispersed by the reflector 14 passes through the optical film set 12 and then into the display panel 11 to provide the display panel 11 with enough light for displaying images.
However, as FIG. 1 shows, the second light 17 undergoes total reflection within the light guide plate 13, exits from one lateral side of the light guide plate 13 and then contacts the outer frame 15. The outer frame 15 can reflect light so that the second light 17 is reflected by the outer frame 15 and travels through the display panel 11 without passing through the optical film set 12. In this way, the second light 17 exiting from the lateral side of the light guide plate 13 is reflected by the outer frame 15 and concentrated at the edge of the display panel 11. The concentration of light will form a bright line at the edge of the display panel 11 which adversely affects the overall images of the conventional liquid crystal display device 10.